Clamp improvement



Nov. 6, 1951 R. F. ROWE CLAMP IMPROVEMENT Filed May 28, 1949 Inve Titer: Robert Fpowe H is Atborn 6 1 Patented Nov. 6, 1951 cumnuraovamr Robert F. Rowe, Fort Wayne, Ind.,

minor to General Electric Company, a corporation of New York Application May 28, 1949, Serial No. 95,902

1 Claim.

This invention relates to electrical induction apparatus, and more particularly to a means for .eifectively holding together a core and clamping means for such apparatus.

In an electrical induction device having a core constructed of stacked laminations, it is necessary that the laminations and the core sections which they form be held firmly together so as to minimize electric core losses and vibrations and prevent any improper orientation of the core sections and laminations.

It is an object of this invention to provide a new and novel means for rigidly holding together the laminated core structure of an electrical induction apparatus, and to provide means which cooperate with the clamping structure to rigidly hold the clamping means and core tightly together.

It is a further object of this invention to provide a new and improved means to rigidly hold a magnetic core in assembled relation in such manner as to result in a material reduction in vibration and noise as compared to prior constructions.

In accomplishment of these objectives, this invention provides a clamping structure for a laminated magnetic core having a means for introducing a subsequently solidified viscous liquid filler or cement into the space between the magnetic core and the clamping device. By the use of this subsequently solidified viscous liquid, the laminated core and clamping means are bound tightly together, resulting in a material reduction in vibration and noise.

The features of my invention which I believe to be novel are set forth with particularity in the appended claim. My invention itself, however, both as to its organization and use, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 shows a perspective view, partially cut away, of an embodiment of this invention as applied to the construction of a fluorescent lamp ballast, while Figs. 2 and 3 show, respectively, a cross section along line 22 of the clamp and transformer core shown in Fig. 1, and an end view of a modifled type of clamp construction.

In the drawing there is shown in Fig. 1, by way of example, a fluorescent lamp ballast I having a core constructed of a plurality of stacked laminations and formed in three main abutting sections 2, 3, and I. The central section 3, which may be constructed of stacked E- and I-shaped laminations, has wound on it a coil I which serves as an autotransiormer, and provides an increased voltage to the fluorescent lamp with which it cooperates. The fluorescent lamps are not shown in the drawing. Serially connected to the coil 5 are the high reactance windings l and I, which are, respectively, mounted on the E- shaped core sections 2 and 4, and which serve to limit the circuit current after conduction through the fluorescent lamp has begun.

In order to hold the laminated cores 2, 3, and 4 tightly together in assembled relation, a clamp 3 is provided on each side of the transformer structure. The clamps 3 serve the dual function of firmly binding together the stacked laminations and of holding the core sections 2, 3, and 4 in proper orientation to one another.

As can be seen in Figs. land 2, clamps 3 may have the form of a U-shaped channel, preferably made of sheet metal, and having a main body 9 and two parallel arms I0, which are opposite one another and extend perpendicularly from the main body 9. The inner edges of upper and lower parallel arms III are respectively bent upwardly and downwardly at II. When the clamps 3 are secured in position by the bolts I2 and I3, or by any other similar means, the stacked laminations are forced together and the core sections 2, 3, and 4 are maintained in rigid relationship to one another. End pieces I4 may be mounted at each end of the core assembly contiguously with the clamps 8.

At either end of the clamping arms III are elliptically-shaped slots I5 through which the bolts l2 and I3 pass. The elliptical shape of the slots I5 allows a rapid and simple aligning of the core sections in proper relation to one another.

In order to more rigidly bind the assembled structure together so as to reduce vibration and noise to a minimum, means are provided for introducing a subsequently solidified viscous filler, such as a suitable cement, for example, into the space between the clamping members 8 and the transformer core. This means comprises holes I6 which are provided at spaced intervals along the surface of the main body 3 of the U-shaped clamping members 8.

As will best be seen in Fig. 2, the main body 9 of the clamps is provided with a plurality of dimples H in the form of slight projections on the inside clamp surface in order to project the clamp surface slightly away from the laminated core. This allows sufficient room for the cement to be extruded into the holes I6, and to have it spread the entire length of the clamp.

There is shown in Fig. 8 a side view or a modified form or clamp which has the major portion or its main body I projecting outwardly from short end sections it which are attached to arms In. The interior race or this projecting surface provides a space between the laminated core and the clamp into which the filler or cement can spread.

After the clamping structure has been assembled as hereinbeiore described, a suitable insulating resinous or cement material It may be injected under pressure into holes IE to fill the void space between the clamps 8 and the laminations. This resinous cement aids materially in holding the clamps and laminations together rigidly, thereby materially reducing vibration and noises.

While there has been shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claim to cover all such changes and modifications as fall within the true spirit and scope of the invention.

-.What I claim as new and desire to secure by Letters Patent of the United States is:

In combination, a laminated magnetic core of generally rectangular shape formed 01' fiat, stacked laminations of magnetic material, the rectangular shape of said core being defined by two long sides and two short sides perpendicular thereto, a pair of sheet metal clamps 01' ohm-- nel-shaped cross-section for holding said magnetic core in assembled relation, each of said channel-shaped clamps having a main body portion and a pair of parallel arms separated from one another by said main body portion and extending perpendicularly therefrom, the pair of parallel arms of each of said clamps extending 4 substantially parallel to the plane of said laminations and embracing the top and bottom surfaces or said core along substantially the entire length or one of said long sides thereof, each of said parallel arms having a plurality of elongated slots formed therein, said laminations having apertures formed therethrough corresponding to said slots in said parallel arms, a plurality of bolts co-operating with said apertures and slots and securing said clamps to said core, the main body portion of each of said clamps extending substantially perpendicularly to the plane of said laminations and forming an enclosed space beyond the stacked edges of said laminations along one of said long sides of said core, each of said main body portions having apertures therein for the introduction of a subsequently solidified viscous filler material into the space between said respective main body portion and the lamination edges adjacent thereto, and :a quantity of said viscous filler material filling said space for binding said clamping members to said laminations and for binding said edges of said laminations together.

ROBERT F. ROWE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 14,113 Thordarson Apr. 18, 1916 1,427,324 Priestley Aug. 29, 1922 1,629,132 Thordarson May 17, 1929 1,726,100 Da Costa Aug. 27, 1929 1,974,588 Snell Sept. 25, 1934 2,425,622 Kronmiller Aug. 12, 1947 2,529,653 Epstein Nov. 14, 1950 

